This invention relates to transmission of rotary power, particularly in printing machines.
In printing machines, particularly though not exclusively in web fed printing machines, there is often a need to move materials printed in two different ways, first a bulk movement fashion e.g. from one printing station to another and secondly to a much smaller extent and generally slower, to position materials to be printed exactly. Mechanical systems for effecting bulk movement do not lend themselves easily to effecting precise positioning and vice versa. Attempts have been made to use dual motion systems in printing presses, for example that shown in U.S. Specification No. 4249688. That specification discloses for example in FIGS. 5 and 6 a system employing a main electric motor and a so called correction electromotor, each of which can be coupled to or de-coupled from a shaft driving a feed drum.